I downloaded a .chm file from the internet, but due to security settings all of the pages had this error message "Navigation to this webpage was canceled." A bit of googling lead me to the official solution of right click, properties..., unblock button. However, due to security settings, my unblock button was missing. The work around is simple. Add it to a .zip file, then extract it. The "it came from the internet" property isn't preserved inside a zip file.